converting PDF

Correct the time sig. See https://musescore.org/en/handbook/time-signatures

I'm guessing you used the PDF conversion feature on musescore.com (possibly accessed via "File / Import PDF" from within MuseScore)? Well, whether you did it that way or using some other program, there is always an intermediate step - first some third party program converts the PDF to MusicXML, then MuseScore reads the resulting MusicXML file. When using the service on musescore.com, that third party program is called Audiveris.

Without seeing the MusicXML file that was used as the intermediate step, it's hard to say exactly what might have happened, but generally speaking, you'd expect to see *far* more glitches in the conversion from PDF to to MusicXML than in the importing of the MusicXML. That's because converting PDF to MusicXML is basically an "artificial intelligence" problem, of a similar difficulty level as voice recognition (harder in some ways, easier in others). Whereas importing a MusicXML file is much more straightforward. It contains the right *kind* of information already; it just needs to be converted from one representation to another.

So, by way of analogy, asking a program to convert PDF to MusicXML is roughly like asking Siri to understand a complex sentence spoken with a thick accent in a noisy room. It will get some stuff, but probably miss a lot too. And that's usually the kind of MusicXML that MuseScore is then being asked to import.

Was the original actually notated as "4/4" or was it perhaps notated as "common time" (with a "C")? If the latte,r I could easily believe the PDF->MusicXML got it wrong - a speck of dust on the paper might have made that "C" look just enough like the cut time symbol to confuse it. And so forth - lots of thigns can go wrong, really.